Crank



Sheets-Sheet v1. W. E. GARD.

CRANE--I (No Mode.)

(No Model.) 2 Sheets-Sheet 2.

W. E. GARD.

GRANK.

180,542,885. Patented July 16, 1895.

UNITED STATES PATENT OFFICE.

WILLIAM E. GARD, OF BROOKLYN, NEW YORK.

CRAN K.

SPECIFICATION forming part of Letters Patent No. 542,885,`dated.]'u1y 16, 1895.

Application nea March s, 1895.

To all whom t may concern:

Be it known that I, WILLIAM E. GARD, a citizen of the United States, residing at Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Cranks; and I do hereby declare the following to be a full, clear, and eX I act description of the invention, such as4 will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to cranks, andv particularly to cranks for bicycles or other similar vehicles; and my invention consists in the novel construction of the crank, in the novel means employed for holding the parts of the crank together, inthe novelmeans employed for permitting access to the crank-bearings, and in the novel form, construction, and arrangement of the parts constituting my improved crank.

The objects of my invention are, first, to provide a crank having as few parts as possible, which shall belight and of simple construction, easily taken apart and put together,

and which `shall not be liable to come apart unintentionally; second, to provide a crank so constructed as to permit of easy access to the bearings and to permit one crank-section to be removed without disturbing the other crank-section; third, to provide simple means for interlocking the ends of the crank-shaft sections and for fastening the two parts of the crank together,V and to so arrange the crankbearings that pressure upon the crank-bearings, due to pressurey upon the pedals, may cause the sections of the crankshaft to be pressed together, thereby removing strain from the device which primarily holds the lshaft-sections together,.reducing the danger of this application, in which the same ref-v erence-numerals indicate the same or corresponding parts, and in which- Figure 1 is a longitudinal section of the crank-bearings and crank-bracket of a bicy- Serial No. 540,634. (No model.)

cle, showing my improved bicycle-crank. Fig. 2 is a similar view showing modifications thereof and in particular a modified method of securing the crank-bearing cones in place, and also means for stiifening the joint between the two crank-sections, so as to resist tendency toward flexure at the joint. Fig. 3 lis an end 4View of one of the sections of the crank-shaft shown in Fig. 2, showing particularly the slots in which the flat keys are placed; and Fig. i illustrates another method for stiffening the joint between the crank-sections against flexure.

.In the drawings, 1 is an ordinary bottom or crank bracket formed upon the lower portion of the frame'ot' the bicycle, which receives the crank-shaft and crank-bearings.

2 and 2 are the crank-arms, which are secured to or formed integrally with the crankshaft sections 3 and 3', which together form the crank-shaft. The ends of these sections 3 and 3 are formed with projecting tongues ortenons 4 and 4", separated by corresponding grooves or mortises, which are so formed that the tongues of one section of the crankshaft fit into the grooves of the other section, the two sections of the crank-shaft being thereby interlocked, so that one must turn with the other.

Various forms of corresponding and interlocking tongues and grooves may be used, and I do not limit myself to any particular form; but if the ends of the sections of the shaft be formed'as shown in the drawings they may be made exactly alike, and if in other respects the two parts of the crank are alike these parts may both be made from one and the same pattern.

The two sections of the crank-shaft are held together and are prevented from separating longitudinally by a screw or key 5, passing through the crank-shaft from one side to the other, and accessible through an aperture 6 in the bracket 1, through which ascrew-driver may be inserted for turning the screwin and out. This aperture may be provided with a suitable cover to prevent the entrance of dust.

Directly upon the sections of 'the crankshaft are placed cones 7 and 7 for the ball bearings in-which the crank-shaft runs, and

into the ends of the bracket 1 are screwed corresponding cones 8 'and 8. Between the ICO cones 7 and 8 and 7 and S are placed the balls 9.

In the form of crank shown in Fig.. 1 shaftsections 3 and 3 are provided with shoulders 10 and 10, slightly larger in diameter than the main portion of the shaft and screwthreaded, and the cones 7 and 7 are arranged to screw upon these shoulders 10 and 10 and against the ends of shoulders 11 and 11', which are slightly largerin diameter than the shoulders 10 and 10, and which determine the positions of these cones, therefore. It necessary lock-nuts may be used to prevent the cones from moving backward; but in general this will be unnecessary, as the direction of rotation of the crank is such as to tend to cause the cones to press more and more tightly against the shoulders 11 and 11.

In the form of crank shown in Fig. 2 the cones 7 and 7 are shown as secured in place by keys or by brazing. They may be secured to the shaft-sections in any other suitable way, or may be formed integral with the shaftsections.

Upon the crank-shaft section 3 is carried the sprocket-wheel 13, which may be secured in place in any ordinary and common manner, as by keys, set-screws, or by shrinking it in place. In the construction shown in Fig. 1 the sprocket-wheel 13 rests upon the shoulder 11 and is putin place before the cones 8 and 7 are put on. In the construction shown in Fig. 2, since the cones 7 and 7' are fixed in place permanently, it is impossible to pass the sprocket-wheel and cones 8 and 8 over these cones 7 and 7' unless the sprocketwheel and the cones 8 and Sbe made excessively large, and I have made the crank-arms with a more gradual curve, so that the cones and the sprccketwheel may be put in place by passing them over the crank-arms.

It will be noted that the cones 7 and 8 and 7 and 8 are so placed with reference to each other that the pressure of the bearing-surfaces tends to press the sections of the crank together, and therefore takes from the screw 5 a large portion of the strain that might otherwise come upon it should there be any tendency of the crank-sections to separate longitudinally. The screw 5, therefore, may be made much smaller than would otherwise be advisable. This arrangement of the cones likewise has the additional advantage thatif through any accident the screw 5 should break, the sections of the crank-shaft will not come apart and the bicycle may still be used, the only result, it' any, being a slightly-greater friction at the crank-bearings and aslightlygreater danger of wear at those bearings.

To give rigidity to the joint between the shafts 3 and 3 and to enable it to resist any possible tendency toward fiexure at the joint it may be advisable to use two or more screws 5, placed longitudinally a short distance from each other. The same result may be accomplished in another way. (Shown in Figs. 2 and 3.) Each shaft-section is provided with a thin slit 15 running longitudinally and inline with the center of the screw-hole through which the screw 5 passes. This slitis slightly wider upon the side without the screw-hole than it is upon the side within the screw-hole. A' thin plate or key 16 is inserted in the slit in each shaft-section, the width of this key being such that when driven to the bottom of the slit it will come to or nearly to the edge of the screw-hole. This plate is of such thick ness as to make a drive lit with the lower or inner portion of the slot, which is slightly narrower than the upper or outer portion, while it merely makes a close fit with the corresponding slit in the other crank-shaft section,within which it lies when the two shaftsections are together. These two plates then constitute a practcallycontin nous key, which greatly stiens the joint and prevents any possible bending. The same result may also be accomplished in the manner shown in Fig. 4 by inclosing the sections of the crank-shaft in a closely-fitting sleeve 17 of considerable length. In this sleeve, opposite the ends of the screw 5, are holes through which this screw may be removed; and to prevent the sleeve from turning with respect to the crank-shaft, as well as to prevent the sleeve from covering the ends of the screw 5 and so preventing access thereto the length of the screw 5 should preferably be slightly greater than the diameter of the crankshaft.

In Fig. 2 the ends of the crank-shaft sections are shown enlarged to strengthen them at the joint.

In assembling the parts of the crank and crank-bearings above described, if the construction be that of Fig. 1, the sprocket-wheel 13 is slipped over the end. of the section 3', seated upon the shoulder 11', and is secured in place. The cone 8 is then put upon the section 3', which it lits loosely, and after it the cone 7 which is screwed upon the shoulder 10 until it rests against the end of the shoulder 11. If the sprocket-wheel is too close to the cones 7 and 8' to permit the balls 9 to be putin place between these cones after the cone 7 is in place they may be placed hetween the cones before the cone 7 is quite in place, and the cone 7 may then be screwed down into place. The cones 7 and 8 are then placed upon the section 3 in a similar manner, the balls 9 being placed between them. The two sections ot the crank-shaft are then placed within the bracket 1 and pressed together, the tongues of the one section fitting into the grooves of the other. When they have thus engaged and have been pushed as near together as is possible with the cones 8 and 8 unscrewed, these cones are screwed into the ends of the bracket l, thus forcing the two parts of the crank together. The screw 5 is then inserted through the hole 6 in the bracket and into the screw-hole in the crankshaft and is screwed home, thus securing the parts together finally. y

In assembling the sections of the crank,

IOO

IIO

when constructed as shown in Fig. 2, the operation is in general the same, except thatin this case, since the cones '7 and 7 are rigid upon the sections 3 and 3, the cones S and 8 and the sprocket-wheel must be put in place by passing them over the ends of the crankarms 2 and 2 before the crank-treadles are attached.

If the flat keys 16 are used to stiffen the joint between the crank-sections, they are driven each into the slot in its respective shaft end before the cones are put on and thereafter stay in place. When the two ends of the crank-shafts are put together, each key slips into the slot in the end of the other shaftsection.l If the sleeve i7 is used to stiffen the joint, it is put upon one shaft-section after the cones are in place thereon, and is slipped into the crank-bracket with the shaft-section. The end of the other shaft-section is then inserted into this sleeve and the parts are attached as before, the screw 5 being passed through the holes in the side of the sleeve and into the screw-hole in the crank-shaft.

As shown in Figs. l and 2, the lengths of the shaft-sections 3 and 3 are exactly the same, as the two parts of the crank are designed to be interchangeable, and as the section 3 of the crankshaft has no sprocketlwheel 13 upon it, it follows that it is comparatively easy to gain access to the bearing on that side of the crank by simply unscrewing the cone 8; but if, as is usually the case, the tread of the machine is made as narrow as possible, so that the crankarm 2and sprocketwheel 13 tit closely to the cone S', there is not sufficient room to remove the cone 8 in order to obtain access to the bearing upon its side of the crank. Access to this bearing may be gained by removing the screw 5 and then drawing out the section 3 of the crank-shaft, at the same time unscrewing the cone 8', and this may be done without in the least disturbing the bearing upon' the other side of the crank.

It will often happen that it is more important to have as great a distance as practicable between the crank-bearings than it is to have the two parts of the crank interchangeable. Where such is the case the length of the bracket l will be such that the cone 8 is very close to the crank-arm 2; but in this case access to the bearing may be obtained in the same manner as to the bearing upon the sprocket side of the crank and without in the least disturbing the bearing on that side and the sprocket-Wheel.

My invention is not limited in its application to bicycles and similar vehicles, but may be applied to other machinery driven by cranks. Neither is it limited to ball-bearings, but may be used with other types of bearingsas, for instance, the ordinary conical bearin gs.

Having thus completely described my invention, what I claim, and desire to secure by Letters Patent, is-

1. In a crank, the combination, with two crank arms, and two crank shaft sections, secured each`to one of said crank arms, and having ends adapted to interlock, of independent bearing cones mounted upon said crank shaft sections, and facing toward the crank arms, and other bearing cones, suitably supported and adapted to engage with said shaft cones, and facing toward the center ofthe crankshaft, substantially as described.

2. In a crank, the combination, with two crank arms, and two crank shaft sections, secured each to one of said crank arms, and having ends adapted to interlock, of independent bearing cones'mounted upon saidcrank shaft sections, and facing toward the crank arms,

other bearing cones, suitably supported and adapted to engage with said shaft cones, and facing toward the center of the crank shaft, and a key, passing through the interlocking ends of said shaft sections and adapted to hold the same together, substantially as described.

3. In a crank, the combination, with two crank arms, and two crank shaft sections, secured each to one of said crank arms, and having mortised and tenoned ends adapted to interlock, of independent bearing cones mount-- ed upon said crank shaft sections, and facing toward the crank arms, other bearing cones, suitably supported and adapted to engage with said shaft cones, and facing toward the center of the crank shaft, and a screw passing through the interlocking ends of said shaft sections and adapted to hold the same together, substantially as described.

4. In a crank, the combination, with two crank arms, and two crank shaft sections, secured each to one of said crank arms, and hav- ICO ing ends adapted tointerlock, of independent bearing cones mounted upon said crank shaft sections, and facing toward the crank arms, other bearing cones, suitably supported and adapted to engage with said shaft cones, and facing toward the center of the crank shaft, and means for stiffening the joint between said crank shaft sections at said joint and preventing flexure thcreat, substantially as described.

5. In a crank, the combination, with two crank arms, and two crank shaft sections, secured each to one of said crank arms, having ends adapted to interlock, and having in said ends longitudinal and registering slots adapted to receive keys, of bearing cones mounted upon said crank shaft sections, other bearing cones suitably supported and adapted to engage with said shaft'cones, flat keys, lying within the slots in the ends of said shaft sections, and arranged to stiifen the joint between said shaft sections and prevent fiexure 'thereat, and a key, passing through the interlocking ends of said shaft sections and holding the same together, substantially as described.

6. The herein described crank, consisting of two separable crank sections, each consistcrank sections together, substantially as de- Io ing of a crank arm having secured rigidly scribed.

In testimony whereof I alix my signature in presence of two witnesses.

WILLIAM E. GARD. lVitnesses:

JAMES S, GREVES, HARRY M. MARBLE. 

